By 1893, development of the working submarine was well advanced, and the US Naval Board recognized that there was a place for the submarine in naval warfare, and laid down a set of requirements for naval submarines. These requirements were met by a boat of Holland's design, and in 1895 he was awarded a contract to build a submarine boat for the US Government.
Development proceeded rapidly from here, and the design destined to become the Royal Navy's Holland No. 1 was, it is thought, America's Holland Number 10 - known as the Adder Class. It was fitted with a 4hp Brayton petrol engine.
Working drawings supplied to Vickers had many discrepancies and in some particulars were obviously incorrect. But building went on to these plans, and it was only after the boat almost turned on end during dock trials that Vickers were allowed to make modifications. The problems were due, in part, to the difficulties of communication with the Holland Boat Company, and the fact that construction of the RN Holland 1 was ahead of the prototype Adder Class and the drawings had therefore not been proved.
